Double-Acting Gas Suspension System

ABSTRACT

A suspension system for use with a motorcycle includes a single body having two double-acting pneumatic cylinders in axial alignment therein. The suspension system may be sold in a kit, and may be retrofitted on an existing OEM motorcycle front wheel fork.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. Ser. No. 11/530,900filed Sep. 12, 2006, which is expressly incorporated by referenceherein.

BACKGROUND AND FIELD OF INVENTION

This invention generally relates to vehicle suspension systems. Moreparticularly, in an illustrated embodiment, the invention is directed toair suspension systems for motorcycle suspensions.

In general terms, motorcycles typically include a main frame to whichthe engine is attached. One or more sub-frames or support-like elementscan be movably attached to the main frame, each of which can be adaptedto hold one of the motorcycle wheels. The moving sub-frames may permitthe motorcycle front and rear wheels to move relative to the main frame.A suspension system may also be used to maintain the height of themotorcycle.

Traditionally, motorcycle suspension systems for street bikes haveincluded one or more springs (typically coil springs) and a hydraulicdamper unit applied to each of the front and rear wheel to provide thelift and dampening needed to suspend the vehicle and control movement ofthe wheels during compression and rebound of the wheels. Such a springand damper unit may be fastened between a swing arm and main frame inthe rear of the motorcycle to control the rear wheel assembly andassociated parts. Also, a spring and damper unit may be positionedinside a telescoping fork assembly to control the front wheel. Anotherform of a front fork, referred to as a “springer” fork, includes aspring suspension operating between two pairs of parallel fork membersin a well known manner.

Other suspension systems may use air in place of or in addition to thespring. These systems are often called air-ride suspension systems, andmay use rubber air bags as springs and may further be charged using acompressed air system. Compressed air may be varied to control the rideheight and the ride characteristics (i.e. firmness) of the motorcycle.However, the ride will inherently get firmer as the air pressureincreases in these systems.

SUMMARY OF INVENTION

The present invention relates to a suspension system having adouble-acting air cylinder. In one illustrative embodiment, the doubleacting cylinder is a single cylinder positioned between the front wheelof a motorcycle and the motorcycle main frame. In another embodiment,the double acting cylinder is a single cylinder positioned between therear wheel of the motorcycle and the motorcycle main frame. In yetanother embodiment, two or more double-acting cylinders are axiallyaligned and provide two or more chambers having compressed gas forcontrolling the suspension characteristics in a motorcycle.

The system disclosed herein could be applied to other vehicles orsuspension systems, such as those found in autos and trailers.Accordingly, as referred to herein, the term “motorcycle” and the likemay be substituted by “vehicle”, “auto”, “trailer”, or any other usethat could incorporate the suspension system disclosed herein. Furtherfeatures and advantages of the invention will be readily apparent fromthe specification and from the drawings.

Moreover, although the illustrated embodiments relate to a suspensionsystem for a front wheel, it should be understood that the conceptsdescribed herein can be applied to a rear wheel suspension system withfew or no modifications, and rear wheel suspension systems are withinthe scope of the disclosure.

Additional features of the disclosure will become apparent to thoseskilled in the art upon consideration of the following detaileddescription of preferred embodiments exemplifying the best mode ofcarrying out the invention as presently perceived.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description particularly refers to the accompanying figuresin which:

FIG. 1 shows a prior art motorcycle frame and front wheel having a priorart suspension system connected thereto;

FIG. 2 shows a front view of a gas suspension system according to oneembodiment of the present invention;

FIG. 3 is another front view of the gas suspension system of FIG. 2;

FIG. 4 is an enlarged view of a midsection of the suspension system ofFIGS. 1-2;

FIG. 5 is an enlarged view of a second end (end cap) of the suspensionsystem of FIGS. 1-2;

FIG. 6 is an enlarged view of a first end of the suspension system ofFIGS. 1-2; and

FIG. 7 is a schematic view of the circuit that can be used to operatethe gas suspension system of FIGS. 1-6.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a well-known main frame 10 and front wheel support 12for a motorcycle 14. Such a main frame 10 and front wheel support 12function together in a well known manner and a number of suspensionsystems have been proposed, designed and marketed which providesuspension functions to the front wheel support 12 of such a motorcycle14. Generally, the front wheel support 12 is connected to a suspensioncomponent 16 that absorbs forces resulting from the front wheel'smovement or contact with objects during operation of the motorcycle 14.A suspension component 15 may be coupled to front wheel support 12, ormay be connected to and operate between main frame 10 and front wheelsupport 12 (not shown). In yet another non-illustrated embodiment,suspension component 15 may be connected between main frame 10 and arear wheel frame.

FIG. 2 shows one embodiment of the proposed suspension component 16,wherein the suspension component includes a housing 17 having a firstend 19 and a second end 21. First end 19 is illustratively configured tobe connected to the main frame 10 or wheel support 12 of the motorcycle,and second end 21 is illustratively configured to connect to the wheel(either front or rear) support. In the illustrated embodiment,suspension component 16 comprises at least a part of the frontsuspension assembly of the motorcycle, and compresses and extends toadjust for inconsistencies in the road, allowing the front (or rear)tire to maintain contact with the road for better handling and brakingwithout the rider feeling the up-and-down movement of the wheel.

As can be seen in FIG. 2, two double-acting cylinders 18, 20 are housedwithin housing 17. In such an embodiment, double-acting cylinders 18, 20are arranged coaxially along axis 23 and pistons 25, 27 move axiallytogether relative to housing 17. Suspension component 16 is in pneumaticcommunication with a pneumatic system (shown in schematic form in FIG.7) that provides compressed gas to the double-acting cylinders 18, 20.In the illustrated embodiment, air is disclosed as the compressed gas.However, it should be understood that the use of other gases is withinthe scope of the invention.

Housing 17 of suspension component 16 is capable of holding pressurizedair. Although the illustrated housing defines a pair of axially alignedair cylinders 18, 20, it is contemplated that other arrangements arepossible, and within the scope of the invention. Moreover, it ispossible for a single air cylinder 18 to be used, rather than the use oftwo axially aligned air cylinders. Accordingly, it should be understoodthat embodiments described herein that disclose two double-actingcylinders can also be configured as a single double-acting cylinder.However, the use of more than one axially aligned air cylinder, such asdescribed herein, provides the advantage of greater resistance over asmaller stroke range.

As shown in FIGS. 2-6, disposed within the air cylinders 18, 20 arepistons 25, 27 respectively, which are sealed (e.g. with bi-directionalseals) in the cylinders so as to prevent loss of air pressure. Suchpistons are positioned to reciprocate within the cylinder bores. Pistons25, 27 are connected via piston rod 29. A second rod 49 extends frompiston 27 toward and through second end 21. Piston rod 29 and second rod49 may or may not be directly connected. As shown in the illustrativeexamples, piston rod 29 connects to one side of piston 27, and secondrod 49 connects to an opposite side of piston 27. Double rod seals 51,53 are shown housed within midsection 55 (shown enlarged in FIG. 4) andend cap 57 (shown enlarged in FIG. 5), respectively.

In the illustrated example, piston rod 29 is a hollow shaft having achannel 37 formed therein. Additionally, a port 31 is positioned atfirst end 19 for accepting compressed air into the housing 17 and intochamber 33 of cylinder 18. As compressed air fills chamber 33, piston 25is urged toward midsection 55. As compressed air enters into chamber 33,it will also be directed through channel 37, illustratively boredthrough the axial center of piston rod 29. This compressed air is thendirected through port 39 into chamber 41, providing for simultaneouscompression of chambers 33, 41 (referred to herein as “lift” chambers).Opposing chambers 43, 45 (also referred to herein as “rebound chambers”)may be filled with a compressed gas or ambient air, as further disclosedbelow. The resulting effect is that both pistons 25, 27 will bepositioned within their respective double-acting cylinders 18, 20, andsuspended by the compressed air in the lift chambers 33, 41 and reboundchambers 43, 45. When pressurized air enters lift chambers 33, 41,pistons 25, 27 are forced toward second end 21 of suspension component16, thereby causing piston rod 29 to extend. Such extension ofsuspension component 16 can also provide for raising or lowering of theentire motorcycle.

Compressed air to suspension component 16 is illustratively providedwith a system (and variations) 22 such as that shown in FIGS. 7-7D. Asseen in FIG. 7, system 22 comprises a relay 24 connected to a battery 26(illustratively the motorcycle battery). Closing relay 24 permitselectricity from battery 26 to operate an air motor or compressor 28. Inone embodiment, the relay 24 is in the same circuit as the ignitionswitch; therefore, the activation of the ignition switch closes relay 24and permits operation of compressor 28.

System 22 may be configured such as that shown in FIG. 7A, whereincompressor 28 is configured to supply compressed air to a volume chamber30. A filter 32 may also be incorporated into system 22 to filterimpurities, such as particulate matter and oil. Pressure in volumechamber 30 is set by an operator pressing one of buttons 40 until thedesired pressure (and ride characteristics) are achieved. A check valve36 can be incorporated to retain the air in volume chamber 30. Volumechamber 30 may be a separate chamber or may be part of the motorcycleframe, such that a frame member of the motorcycle functions as a volumechamber and could contain pressurized air.

As shown in FIG. 7, a solenoid valve 38 may be incorporated in system22. Solenoid 38 permits an operator to dump pressure from the system,thereby softening the ride and/or lowering the ride height for theoperator. Furthermore, system 22 could be configured such thatcompressor 28 will not operate unless the ignition switch is turned tothe “lights on” position.

Push buttons 40 can also be provided for controlling the compressed airin the double acting cylinders. Such push buttons 40 may be located in aposition convenient to a motorcycle rider, such as near or on the handlebars. The push buttons 40 control the compressed gas pressure in doubleacting cylinders 18, 20 by either directing additional compressed air tobe added to double acting cylinders 18, 20 or bleeding air fromcylinders 18, 20. By varying the amount of compressed air in cylinders18, 20, the ride height, ride quality, and/or spring rate of thecylinders can be modified to the user's liking or needs.

Another embodiment of the invention is shown in FIG. 7B. In such anembodiment, pressure in rebound chambers 43, 45 (visible in FIGS. 2-3)can be controlled simply via a check valve 42, shown in FIG. 7B. Such acheck valve 42 would allow for the intake of ambient air into reboundchambers 43, 45 when the system is not energized (i.e. chambers 33, 41are not energized with compressed air). For example, during the initialinstallation of the check valve, the initial suspension travel(extension) will suction air through check valve 42 into chamber 45, andthe check valve will seat. This air is now trapped and will act as anair spring and biasing element. When the system is later energized,check valve 42 would seal, and rebound chamber 45 would provide anopposing bias as lift chambers 33, 41 are further energized.

For the embodiments disclosed herein, it is possible (and sometimespreferable) for a check valve to be installed on both rebound chambers43, 45 to trap air. Consequently, either or both rebound chambers 43, 45could be charged with pressurized air depending on the use or desiredsuspension qualities. For example, when a firmer ride is desired, bothrebound chambers 43, 45 can be charged with compressed gas or air.

In yet another alternative embodiment, shown in FIG. 7C, reboundchambers 43, 45 may be pre-pressurized to a pre-selected level prior todelivery to the consumer. A desirable pre-selected pressurization levelhas been determined to be approximately three pounds-per-square-inch,but any pressure above zero psi and below 10 psi is contemplated to bewithin the scope of the invention.

In a further embodiment illustrated in FIG. 7D, pressurized air can besupplied to rebound chambers 43, 45 at a secondary pressure to offsetthe primary pressure in lift chambers 33, 41. Such a secondary airpressure is generated by a biasing regulator 44. One example of abiasing regulator 44 is a Type 200 Precision Air Relay manufactured byControlAir Inc.; more information can be obtained at www.controlair.com.The biasing regulator 44 is supplied with pressurized air from system 22and may be preset by the system manufacturer, motorcycle manufacturer orin the alternative, adjusted for ride characteristics by the operator.

In the embodiment illustrated in FIG. 7D, a biasing regulator 44 isconnected to lift chambers 33, 41, and is configured to deliver asecondary pressure at a pressure relative to that of lift chambers 33,41 to rebound chambers 43, 45. Such a configuration is provided in partto offset the pressure in lift chambers 33, 41. This pressure in reboundchambers 43, 45 controls the rebound of the suspension component, and ofthe front or rear end of the motorcycle as a whole.

Biasing regulator 44 further provides a counterbalance to the air springeffect on an opposite side (i.e. rebound chambers 43, 45) of the pistonas that of the main air suspension pressure (lift chambers 33, 41). Thebiasing regulator maintains a ratio or proportional counterforce to theair spring unloaded setting, and thus, provides the rebound control in amanner which tracks any changes in the main air spring pressure. Airfunctions as an ideal spring due to the fact that the spring rate isprogressive during compression in contrast to most springs, which have alinear fixed compression rate.

In the disclosed embodiment, first end 19 (and second end 21), shown inFIGS. 2-3, may be fitted with a self-lubricating bearing material on thebearing contact surface 50 that permits extended function. Furthermore,the tolerances for first and second ends 19, 21 may be such that thesuspension component 18 may be installed on a variety of motorcycles andeven on frames having slight offsets or imperfections. Moreover, due tothe small size of suspension component 16 (less than the diameter of astandard monoshock 3.25″ and the same overall length), the presentlydisclosed system may be substituted for nearly any existing suspensioncomponent.

In the disclosed embodiment, a pair of suspension components 16 may besold as a kit that can be retrofitted on a sport bike having themanufacturer's OEM standard monoshock (also referred to as a fork tube).The kit may include all of the pneumatic components described herein andillustrated in FIG. 7, including push buttons 40. The kit may alsoinclude instructions for installation. The kit may or may not include abiasing regulator, since such an addition would be an additional costfor the consumer. In the non-biasing regulator kit, other embodimentsdiscussed herein could be sold as a kit, e.g. the embodiment in whichchambers 43, 45 are pre-pressurized prior to delivery of the kit. Thekit may also include a volume chamber and/or a compressor that isinstallable on the motorcycle. The kit may be combined with a rearpneumatic suspension system for a motorcycle as well.

An exemplary installation process may include the following steps. Thelower shock retainer bolts, near the axle, are removed. The threadedcaps of the existing OEM standard shock are unscrewed and the internalcomponents of the OEM shock are removed from the housing. A suspensioncomponent 16, shown in FIGS. 2-3, is inserted in the place of each theinternal suspension components of the OEM standard shock, and theappropriate pneumatic connections made to a volume chamber, acompressor, buttons 40, or otherwise, depending on the particular kitpurchased. A decorative cap 60, visible in FIG. 2, may be provided forcovering the pneumatic fittings of suspension component 16.

While the disclosure is susceptible to various modifications andalternative forms, specific exemplary embodiments thereof have beenshown by way of example in the drawings and have herein been describedin detail. It should be understood, however, that there is no intent tolimit the disclosure to the particular embodiments disclosed, but on thecontrary, the intention is to cover all modifications, equivalents, andalternatives falling within the spirit and scope of the disclosure andas further defined by the following claims.

1. A kit comprising: a pair of pneumatic suspension componentsconfigured to be positioned within two manufacturer's original forktubes in a front-end motorcycle suspension system, each of the pneumaticsuspension components defining a single body housing having twodouble-acting pneumatic cylinders in axial alignment therein, whereineach of the pneumatic suspension components includes a sealed reboundchamber.
 2. The kit of claim 1, further comprising a compressor capableof being coupled to the double-acting pneumatic cylinders.
 3. The kit ofclaim 1, wherein the pair of suspension components are in pneumaticcommunication with each other.
 4. The kit of claim 1, wherein each ofthe double-acting pneumatic cylinders defines a lift chamber, and thetwo lift chambers in each suspension component are in pneumaticcommunication with each other.
 5. The kit of claim 4, wherein the twolift chambers communicate via an internal port disposed inside a pistonrod.
 6. The kit of claim 4, wherein each lift chamber is incommunication with a compressed air source.
 7. The kit of claim 1,further comprising a check valve coupled to one of the rebound chambers,the check valve permitting the intake of ambient air into the reboundchamber.
 8. The kit of claim 7, wherein the second chamber ispre-pressurized to a predetermined pressure.
 9. The kit of claim 8,wherein the predetermined pressure is above zero and below fifty poundsper square inch.
 10. The kit of claim 1, further comprising a biasingregulator that maintains the pneumatic pressure of a first cylinderchamber as a ratio of the pneumatic pressure of a second cylinderchamber.
 11. The kit of claim 10, wherein the biasing regulator isadjustable.
 12. A kit comprising: a pneumatic suspension componentconfigured to be positioned within an existing front-end motorcycle forktube, the pneumatic suspension component defining a single body housinghaving two double-acting pneumatic cylinders in axial alignment therein.13. The kit of claim 12, further comprising a compressor coupled to thedouble-acting pneumatic cylinders.
 14. The kit of claim 12, wherein eachof the double-acting pneumatic cylinders defines a lift chamber, and thetwo lift chambers are in pneumatic communication with each other. 15.The kit of claim 14, wherein the lift chambers communicate via aninternal port disposed inside a piston rod.
 16. The kit of claim 14,wherein the lift chambers are in communication with a compressed airsource.
 17. The kit of claim 12, wherein the pneumatic suspensioncomponent defines a rebound chamber.
 18. The kit of claim 17, furthercomprising a check valve coupled to one of the rebound chambers, thecheck valve permitting the intake of ambient air into the reboundchamber.
 19. The kit of claim 17, further comprising a biasing regulatorthat maintains the pneumatic pressure of the rebound chamber as a ratioof the pneumatic pressure of a lift chamber in the pneumatic suspensioncomponent.
 20. The kit of claim 19, wherein the biasing regulator isadjustable.